Lin et al. 2023 - Lead and mercury in breast milk from a Taiwanese human milk bank cohort

Lin and colleagues measured Pb, total Hg, and MeHg in 228 breast milk samples longitudinally donated by 39 lactating women recruited through the Taiwan Southern Human Milk Bank (TSHMB) at National Cheng Kung University Hospital, and estimated infant health risk from breastfeeding using Monte Carlo simulation. Although samples were collected through a milk bank, the donors are mothers in the general lactating population and the findings characterise breast-milk Pb/Hg exposure for breastfed infants of those mothers and for vulnerable recipients of bank-donated milk. The authors describe this as the first cohort study of heavy metals in a human milk bank.

Key numbers

• Breast milk Pb (n=228): mean 6.49 ± 5.23 µg/L, range 0.55-49.70 µg/L (Table 2).
• Breast milk total Hg (n=228): mean 0.76 ± 0.98 µg/L, range 0.07-14.20 µg/L (Table 2).
• MeHg was not detected in any of the 228 breast milk samples (Table 2 footnote).
• Maternal blood Pb (n=14): 2.12 ± 1.05 µg/L; maternal blood Hg (n=14): 7.35 ± 2.16 µg/L (Table 2).
• 42.9% of breast milk samples exceeded the WHO suggestion of <5 µg/L Pb (Discussion).
• Living near sources of air pollution within 1 km was associated with higher breast-milk Pb (10.3 ± 7.00 µg/L vs 5.49 ± 3.23 µg/L; p=0.025) (Table 3).
• House dust contact without a mask was associated with higher Pb (9.43 ± 6.42 vs 5.06 ± 2.68 µg/L; p=0.024) (Table 3).
• Cosmetic users had higher mean Pb (9.23 ± 6.12 vs 4.82 ± 2.58 µg/L; p=0.012) and lipstick users had higher mean Pb (10.9 ± 6.42 vs 4.85 ± 2.46 µg/L; p=0.002) (Table 3).
• Dietary intake of viscera was associated with higher Pb (10.2 ± 5.92 vs 4.54 ± 2.51 µg/L; p<0.001) and higher Hg (0.84 ± 0.39 vs 0.57 ± 0.18 µg/L; p=0.043); large fish (sharks/marlin/tuna/oilfish) consumption was associated with higher Hg (1.11 ± 0.45 vs 0.62 ± 0.24 µg/L; p=0.029) (Table 4).
• Estimated daily intake for infants: Pb EDI 0.628 µg/kg-BW/day, Hg EDI 0.069 µg/kg-BW/day (Table 5).
• Pb hazard quotient (against EFSA BMDL01 of 0.5 µg/kg-BW/day, EFSA 2010): 50th percentile 0.989, 95th 3.782, 99th 7.572.
• Hg hazard quotient (against WHO PTWI of 4 µg/kg-BW/week, WHO 2011): 50th 0.097, 95th 0.326, 99th 0.609.
• Combined hazard index at the 95th percentile HI = 1.37 > 1, indicating an unacceptable non-cancerous health risk for breastfed infants; Pb concentration contributed 52.8% of variance in HI and infant intake amount 34.2% (sensitivity analysis).

Methods (brief)

228 breast milk samples were collected longitudinally from 39 donor mothers every 1-2 weeks up to 9 months postpartum, with monthly infant body weight and milk consumption recorded for exposure calculation. Pb was quantified by ICP-MS (PerkinElmer Nexion 2000) per Taiwan FDA MOHWH0023.00, total Hg by automatic mercury analyzer (MA-2000) using thermal decomposition / amalgamation / atomic absorption (USEPA 7473), and MeHg by LC/ICP-MS (PerkinElmer Nexion 2000) per Taiwan FDA MOHWH0018.00. Method detection limits in milk were 0.047 µg/L for Pb, 0.132 µg/L for Hg, and 0.082 µg/L for MeHg, with recoveries of 103%, 109%, and 89%. Maternal blood (n=14) was analysed by the same methods. Infant exposure was estimated via Monte Carlo simulation in @Risk 7.5.1 (Palisade Corp.), with HQ computed against EFSA BMDL01 for Pb and WHO PTWI for Hg.

Implications

Certification: Exposure-context evidence for breast milk and for donor-milk recipients. Not a product-market source.

Courses: Useful for showing how breast-milk concentration data and infant body-weight and milk-consumption profiles are translated into probabilistic infant exposure estimates, and how maternal lifestyle and dietary predictors propagate to breast-milk Pb and Hg.

App: Can support breast-milk exposure context with Taiwan-specific caveats; maternal predictors (residential pollution proximity, house-dust contact, cosmetic and lipstick use, viscera and large-fish consumption) are mechanistically generalisable for the metals/lead and metals/mercury-total pages.

Wiki pages this source may touch

• Breastmilk
• Infant Food General
• Lead
• Mercury, Total
• Methylmercury

Verification notes

The source discusses cosmetic and lipstick use as predictors of breast-milk Pb; this is not brand-level cosmetics evidence and must not be routed as a cosmetic product occurrence source. MeHg was measured but not detected in any sample; the wiki page reports the analytical result rather than treating it as absent measurement.

Page history

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